Remember 3 years ago when Tyrande invoked the Night Warrior and all Night Elf players thought they'd finally get some retribution? What a joke. Worst of all is that she's been portrayed like a mad woman for wanting justice. Now that she chose 'renewal' (which basically means letting the Horde get away with it, again) over vengeance, all chances of seeing retribution are gone.
Imo, to have at least some form of closure, the Kaldorei should give the Horde an ultimatum. Depart from Night Elf lands and never return, or be hunted down. These lands include Darkshore, Ashenvale, Mount Hyjal and Moonglade. I'm sure the mages and druids could construct some natural/magical barrier between Ashenvale and the Barrens/Azshara, to prevent any trespassing. Malfurion should also kick the Tauren and Trolls out of the Cenarion Circle. Letting them join was dumb decision to begin with.
However, knowing Blizzard, the Horde will be invading Ashenvale again in 3-5 years. And they again will get away with it scot free.